Despite the efforts of medical device manufacturers to reduce the coefficient of friction for their catheters, especially those intended for introduction through a sphincter or narrow body lumen, there is very often a problem with discomfort to the patient or trauma to delicate or sensitive tissues as the catheter is being advanced. Lubricants and lubricious polymers or other coatings can reduce these effects, but not always to a sufficient degree. In the biliary system, for example, passing a biliary catheter through the Papilla of Vater and into the common bile duct very often results in swelling and subsequent closure of the opening, compromising normal drainage and making subsequent access difficult. Similar problems with discomfort or edema can be experienced by the patients when other anatomical sites are being accessed, for example, in the nasal passages, urethra, rectum, etc. While patient comfort may not be an issue when navigating internally such as within the biliary tree, the introduced device may be difficult or even impossible to advance from frictional forces acting against it, especially since these obstructions and narrowed passages often cannot be adequately visualized.
One approach to reduce patient discomfort when introducing a catheter or similar device, is to include a sheath or sleeve which is laid down by the advancing device to prevent frictional contact between the device and the delicate lining of the bodily passage. A urethral catheter with an outer sleeve is disclosed in U.S. Pat. No. 5,779,670 to Bidwell in which the latex sleeve is fixedly and sealingly attached to the inside of the catheter by a sliding retention sled and to the outside of the catheter by a slidable collar. The sleeve allows relative movement of the catheter to the urethra without the normal friction that causes patient discomfort during introduction and wearing of the device. A lubricant fills the space created between the sleeve and the catheter which is intended to further reduce friction between the two surfaces. While the '670 concept may be suitable to traverse the urethra for purposes of draining the bladder, it is not useful for other anatomical sites and procedures in which having the sleeve attached to the inside of the catheter is not desired, such as in an ERCP (Endoscopic Retrograde Cholangiopancreatography) procedure or placement of a nasal-jejunal feeding tube or colonic decompression catheter. In these procedures, the sleeve might be used advantageously in combination with the introduced device to access a narrow duct or opening, to cannulate a stricture, or navigate over folds of tissue, but its eventual removal from the inner member passageway is typically required to complete the procedure. In the case of a feeding or decompression tube, continued presence of the sleeve over the catheter would block critical side holes. For these reasons, the Bidwell concept is not suitable for the introduction of a second medical device into the body.
Besides the biliary system, other sites within the body present an opportunity for improved patient comfort and reduced trauma by the reduction of friction during the introduction of a device. For example, the nasal passages are especially sensitive and recent trends have brought about an increase in the number of devices, such as endoscopes and tubes, being introduced via that route concomitant with the use of analgesics or sedatives to reduce patient discomfort. Another situation where reduction of friction would be important is in the lower gastrointestinal tract where folds within the colon can provide sufficient resistance to an introduced catheter or other device where in many cases, the tip of the catheter bends back on itself, rather than continuing to advance to the treatment site. Therefore, what is needed is a friction-reducing introducer apparatus that can be used with a separate catheter, sheath, or other medical devices to permit the safe and comfortable passageway thereof into and/or through a bodily passage, and is removable from the treatment site so as not to possibly interfere with the function of the introduced device(s).